Fuel pump

Abstract

Provided is a fuel pump including: a pump head (23); a plunger barrel (32) in which a support hole (38) is provided, and one end section of which in the axial direction of the support hole (38) is screw-fastened into the pump head (23); a plunger (41) that is supported in the support hole (38) so as to be freely movable in the axial direction; a pressurization chamber (56) that is defined by one end of the support hole (38) and one end of the plunger (41); a fuel discharge passage (73) one end of which communicates with the pressurization chamber (56); and a fuel suction passage (70) one end of which communicates with the pressurization chamber (56).

The invention claimed is: 
     
       1. A fuel pump comprising:
 a pump head; 
 a plunger barrel that is provided with a support hole and in which one end portion side of the support hole in an axial direction is screwed to the pump head; 
 a plunger that is supported by the support hole so as to be movable along the axial direction; 
 a pressurization chamber partitioned by one end portion of the support hole and one end portion of the plunger; 
 a fuel channel of which one end portion communicates with the pressurization chamber and an other end portion communicates with a discharge channel; 
 a suction channel of which one end portion communicates with the fuel channel; and 
 a discharge valve having a first portion provided within the discharge channel, and a second portion extending from the first portion and provided within the fuel channel, 
 wherein 
 the fuel channel and the suction channel communicate with each other at an intersection point where they intersect with each other, 
 the fuel channel extends in a first direction, 
 the suction channel extends in a second direction intersecting the first direction, and 
 the second portion extends in the first direction from a base of the first portion to the intersection point in the fuel channel, 
 the discharge valve closes when a pressure in the pressurized chamber is less than a predetermined pressure, and disconnects the discharge channel and the fuel channel; 
 the discharge valve opens when the pressure in the pressurized chamber exceeds the predetermined pressure, and connects the discharge channel and the fuel channel. 
 
     
     
       2. The fuel pump according to  claim 1 , wherein
 the fuel channel is disposed in a straight line with respect to the support hole, and 
 the suction channel is disposed along a direction orthogonal to the fuel discharge channel. 
 
     
     
       3. The fuel pump according to  claim 2 , wherein
 the plunger barrel includes a small diameter portion and a large diameter portion provided on the other end portion side in the axial direction from the small diameter portion, 
 a male thread portion is formed on an outer peripheral portion of the small diameter portion, 
 the pump head is provided with one or more accommodation holes, 
 a female thread portion is formed on an inner peripheral surface of the one or more accommodation holes, 
 the plunger barrel is screwed to the pump head by allowing the male thread portion to be screwed into the female thread portion, 
 a ring-shaped sealing portion is formed between an end surface of the small diameter portion and an end surface of the one or more accommodation holes, and 
 an inner diameter of the sealing portion is larger than an inner diameter of the support hole. 
 
     
     
       4. The fuel pump according to  claim 2 , wherein
 the plunger barrel is provided with an engagement portion that engages with a fastening tool on the other end portion side in the axial direction so as to rotate the plunger barrel. 
 
     
     
       5. The fuel pump according to  claim 1 , wherein
 the plunger barrel includes a small diameter portion and a large diameter portion provided on the other end portion side in the axial direction from the small diameter portion, 
 a male thread portion is formed on an outer peripheral portion of the small diameter portion, 
 the pump head is provided with one or more accommodation holes, 
 a female thread portion is formed on an inner peripheral surface of the one or more accommodation holes, 
 the plunger barrel is screwed to the pump head by allowing the male thread portion to be screwed into the female thread portion, 
 a ring-shaped sealing portion is formed between an end surface of the small diameter portion and an end surface of the one or more accommodation holes, and 
 an inner diameter of the sealing portion is larger than an inner diameter of the support hole. 
 
     
     
       6. The fuel pump according to  claim 5 , wherein
 the sealing portion and the support hole form a concentric circle shape. 
 
     
     
       7. The fuel pump according to  claim 6 , wherein
 an outer diameter of the male thread portion is set to be larger than an outer diameter of the sealing portion, and is set in a range of 1.8 times to 2.3 times the inner diameter of the sealing portion. 
 
     
     
       8. The fuel pump according to  claim 6 , wherein
 the one or more accommodation holes include a first hole in which the female thread portion is formed on an inner peripheral surface and a second hole having a diameter larger than a diameter of the first hole, and 
 an outer peripheral portion of the large diameter portion of the plunger barrel is fitted into an inner peripheral surface of the second hole via an O-ring. 
 
     
     
       9. The fuel pump according to  claim 6 , wherein
 the plunger barrel is provided with an engagement portion that engages with a fastening tool on the other end portion side in the axial direction so as to rotate the plunger barrel. 
 
     
     
       10. The fuel pump according to  claim 5 , wherein
 an outer diameter of the male thread portion is set to be larger than an outer diameter of the sealing portion, and is set in a range of 1.8 times to 2.3 times the inner diameter of the sealing portion. 
 
     
     
       11. The fuel pump according to  claim 10 , wherein
 the one or more accommodation holes include a first hole in which the female thread portion is formed on an inner peripheral surface and a second hole having a diameter larger than a diameter of the first hole, and 
 an outer peripheral portion of the large diameter portion of the plunger barrel is fitted into an inner peripheral surface of the second hole via an O-ring. 
 
     
     
       12. The fuel pump according to  claim 10 , wherein
 the plunger barrel is provided with an engagement portion that engages with a fastening tool on the other end portion side in the axial direction so as to rotate the plunger barrel. 
 
     
     
       13. The fuel pump according to  claim 5 , wherein
 the one or more accommodation holes include a first hole in which the female thread portion is formed on an inner peripheral surface and a second hole having a diameter larger than a diameter of the first hole, and 
 an outer peripheral portion of the large diameter portion of the plunger barrel is fitted into an inner peripheral surface of the second hole via an O-ring. 
 
     
     
       14. The fuel pump according to  claim 5 , wherein
 the plunger barrel is provided with an engagement portion that engages with a fastening tool on the other end portion side in the axial direction so as to rotate the plunger barrel. 
 
     
     
       15. The fuel pump according to  claim 1 , wherein
 the plunger barrel is provided with an engagement portion that engages with a fastening tool on the other end portion side in the axial direction so as to rotate the plunger barrel. 
 
     
     
       16. The fuel pump according to  claim 15 , wherein
 one or more compression coil springs that energizes the plunger in a direction to press the plunger against a cam is disposed outside the plunger barrel in a radial direction, and 
 a spring receiving portion of the energizing member is provided on an end surface of the engagement portion. 
 
     
     
       17. The fuel pump according to  claim 1 , wherein
 the plunger barrel is one of a plurality of the plunger barrels that are disposed on the pump head at intervals, and 
 pitches of the plurality of the plunger barrels are set in a range of 5 times to 6 times the inner diameter of the support hole.